■组织病理学是分析动脉粥样硬化斑块的金标准,但由于该方法的破坏性而存在缺陷。离体MRI是对整个斑块成像的非破坏性方法。我们的目的是使用定量高场离体MRI对斑块成分进行分类,以组织学为黄金标准。
■对12例近期TIA或卒中患者手术切除的颈动脉斑块进行11.7TMRI成像。在组织学准备之前,获得了体素大小为30×30×60μm3的定量T1/T2*映射序列和定性T1/T2*梯度回波序列。切片和染色脂质,炎症,出血,和纤维组织。基于组织学染色在组织学和MRI之间匹配的多个水平选择感兴趣区域(ROI)。然后用二次判别分析(QDA)分析每个ROI的MRI参数以进行分类。
■总共965个ROI,在组织学和MRI匹配的70个水平上,根据组织学染色进行登记。在9个斑块中,三个或更多斑块成分可能与MRI共定位,QDA错误分类的平均程度为16.5%。其中一个斑块主要包含纤维组织和脂质,没有错误分类,两个斑块主要含有纤维组织。QDA通常对纤维组织和脂质显示良好的分类,而有出血和炎症的斑块有更多的错误分类。
■11.7T离体高场MRI显示与颈动脉斑块组织学具有良好的视觉一致性。用QDA分析的T1/T2*图是一种有前途的无损方法来分类斑块成分,但是在有出血或炎症的斑块中,错误分类的程度更高。
OBJECTIVE: Histopathology is the gold standard for analysis of atherosclerotic plaques but has drawbacks due to the destructive nature of the method. Ex vivo MRI is a non-destructive method to image whole plaques. Our aim was to use quantitative high field ex vivo MRI to classify plaque components, with histology as gold standard.
METHODS: Surgically resected carotid plaques from 12 patients with recent TIA or stroke were imaged at 11.7 T MRI. Quantitative T1/T2* mapping sequences and qualitative T1/T2* gradient echo sequences with voxel size of 30 × 30 × 60 μm3 were obtained prior to histological preparation, sectioning and staining for lipids, inflammation, hemorrhage, and fibrous tissue. Regions of interest (ROI) were selected based on the histological staining at multiple levels matched between histology and MRI. The MRI parameters of each ROI were then analyzed with quadratic discriminant analysis (QDA) for classification.
RESULTS: A total of 965 ROIs, at 70 levels matched between histology and MRI, were registered based on histological staining. In the nine plaques where three or more plaque components were possible to co-localize with MRI, the mean degree of misclassification by QDA was 16.5 %. One of the plaques contained mostly fibrous tissue and lipids and had no misclassifications, and two plaques mostly contained fibrous tissue. QDA generally showed good classification for fibrous tissue and lipids, whereas plaques with hemorrhage and inflammation had more misclassifications.
CONCLUSIONS: 11.7 T ex vivo high field MRI shows good visual agreement with histology in carotid plaques. T1/T2* maps analyzed with QDA is a promising non-destructive method to classify plaque components, but with a higher degree of misclassifications in plaques with hemorrhage or inflammation.